Turbine arrangement

Abstract

The turbine arrangement includes a turbine including a turbine housing which defines a turbine cavity within which a turbine wheel is supported, an inlet upstream of the wheel and an outlet downstream. The arrangement also includes a flow passage configured to permit gas flow without interacting with the wheel, and a valve member moveable between an open configuration wherein gas may flow through the flow passage, and a closed configuration wherein gas is substantially prevented from flowing, a first actuator portion for moving the valve member between the configurations, and a second actuator portion in gas flow communication with a portion of the arrangement upstream of the wheel via an actuator gas passage. The arrangement is configured such that gas may flow through the actuator gas passage to the second actuator portion, where it acts on the second actuator portion to urge the valve member towards the closed configuration.

What is claimed is: 
     
       1. A turbine arrangement comprising:
 a turbine including turbine housing defining: a turbine cavity within which a turbine wheel is supported for rotation, a turbine inlet upstream of the turbine wheel, and a turbine outlet downstream of the turbine wheel; 
 a flow passage between a location upstream of the turbine wheel and a location downstream of the turbine wheel configured to permit gas to flow from said location upstream of the turbine wheel to said location downstream of the turbine wheel without interacting with the turbine wheel; and 
 a valve arrangement comprising:
 a valve member moveable between open and closed configurations, wherein in the open configuration gas may flow from said location upstream of the turbine wheel to said location downstream of the turbine wheel through the flow passage, and in the closed configuration gas is substantially prevented from flowing through the flow passage; 
 a first actuator portion connectable to an actuator for moving the valve member between the open and closed configurations; and 
 a second actuator portion in gas flow communication with a portion of the turbine arrangement upstream of the turbine wheel via a actuator gas passage; and 
 
 wherein the turbine arrangement is configured such that gas may flow from said portion of the turbine arrangement upstream of the turbine wheel through the actuator gas passage to the second actuator portion, such that the pressure of said gas which flows through the actuator gas passage to the second actuator portion acts on the second actuator portion to urge the valve member towards the closed configuration. 
 
     
     
       2. A turbine arrangement according to  claim 1 , wherein the turbine housing comprises an aperture defining a portion of the flow passage such that when the valve member is in the closed configuration the aperture is covered by the valve member such that the valve member and the turbine housing form a seal that substantially prevents gas flowing through the flow passage. 
     
     
       3. A turbine arrangement according to  claim 2 , wherein the turbine housing defines a valve seat, and wherein, in the closed configuration, the valve member contacts the valve seat to form said seal that substantially prevents gas flowing through the flow passage. 
     
     
       4. A turbine arrangement according to  claim 2 , wherein the valve member moves in a first direction between said open configuration and said closed configuration. 
     
     
       5. A turbine arrangement according to  claim 4 , wherein the second actuator portion moves in a second direction relative to the valve arrangement. 
     
     
       6. A turbine arrangement according to  claim 5 , wherein when the valve member is in the closed configuration, the projected area of the aperture normal to the first direction is larger than the projected area of the second actuator portion normal to the second direction, such that the net force exerted on the valve member urges the valve member towards the open configuration. 
     
     
       7. A turbine arrangement according to  claim 5 , wherein when the valve member is in the closed configuration, the projected area of the aperture normal to the first direction is substantially equal to the projected area of the second actuator portion normal to the second direction, such that zero net force is produced on the valve member. 
     
     
       8. A turbine arrangement according to  claim 5 , wherein when the valve member is in the closed configuration, the projected area of the aperture normal to the first direction is smaller than the projected area of the second actuator portion normal to the second direction, such that the net force exerted on the valve member urges the valve member towards the closed configuration. 
     
     
       9. A turbine arrangement according to  claim 1 , wherein the first actuator portion comprises an arm mounted for rotation such that rotation of the arm causes movement of the valve member between the open and closed configurations. 
     
     
       10. A turbine arrangement according to  claim 1 , wherein the second actuator portion is directly coupled to the valve member. 
     
     
       11. A turbine arrangement according to  claim 1 , wherein the second actuator portion is coupled to the valve member via a linkage. 
     
     
       12. A turbine arrangement according to  claim 1 , wherein the second actuator portion comprises a piston member supported for movement within an actuation chamber, wherein the actuator gas passage connects said portion of the turbine arrangement upstream of the turbine wheel to the actuation chamber, such that gas in the actuation chamber acts on the piston member to urge the piston member to move within the actuation chamber so as to urge the valve member towards the closed configuration. 
     
     
       13. A turbine arrangement according to  claim 12 , wherein gas in the actuation chamber acts on the piston member to urge the piston member to move in a substantially linear manner within the actuation chamber so as to urge the valve member towards the closed configuration. 
     
     
       14. A turbine arrangement according to either  claim 12 , wherein the piston member further comprises piston rings for sealing between the piston member and a wall of the actuation chamber. 
     
     
       15. A turbine arrangement according to  claim 1 , wherein at least one of the second actuator portion and the valve member comprises a curved surface which contacts the other of the second actuator portion and valve member such that an angle of contact between the second actuator portion and the valve member may change as the valve member is moved between the closed and open configurations. 
     
     
       16. A turbine arrangement according to  claim 12 , wherein the piston member comprises a substantially spherical ball. 
     
     
       17. A turbine arrangement according to  claim 1 , wherein the actuator gas passage is defined by a portion of the turbine housing. 
     
     
       18. A turbine arrangement according to  claim 1 , wherein the actuator gas passage is defined by piping external to the turbine housing. 
     
     
       19. A turbine arrangement according to  claim 1 , wherein said portion of the turbine arrangement upstream of the turbine wheel is the turbine inlet, such that the actuator gas passage places the turbine inlet in gas flow communication with the second actuator portion. 
     
     
       20. A turbine arrangement according to  claim 1 , wherein said location upstream of the turbine wheel is the turbine inlet. 
     
     
       21. A turbine arrangement according to  claim 1 , wherein said location downstream of the turbine wheel is the turbine outlet. 
     
     
       22. A turbine arrangement according to  claim 1 , wherein the turbine forms part of a turbocharger or power turbine.